import type { TaskEngine } from './engine.js';
import type { ShortTermStore, DisconnectPolicy } from './types.js';
import type { WorkerManager } from './worker-manager.js';
export interface HeartbeatMonitorOptions {
    workerManager: WorkerManager;
    engine: TaskEngine;
    shortTermStore: ShortTermStore;
    checkIntervalMs?: number;
    heartbeatTimeoutMs?: number;
    defaultDisconnectPolicy?: DisconnectPolicy;
    disconnectGraceMs?: number;
}
export declare class HeartbeatMonitor {
    private workerManager;
    private engine;
    private shortTermStore;
    private checkIntervalMs;
    private heartbeatTimeoutMs;
    private defaultDisconnectPolicy;
    private disconnectGraceMs;
    private timer?;
    private graceTimers;
    constructor(opts: HeartbeatMonitorOptions);
    start(): void;
    stop(): void;
    tick(): Promise<void>;
    /** Cancel grace timer if worker comes back (call from heartbeat handler) */
    cancelGrace(workerId: string): void;
    private _handleTimeout;
    /**
     * Transition a task back to pending through valid state machine transitions.
     * running -> paused -> assigned -> pending
     * assigned -> pending
     * Other states -> try direct pending transition
     */
    private _transitionToPending;
    private _findPathToPending;
    private _startGraceTimer;
}
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